Prior art outboard packed reciprocating plunger pumps are generally characterized by "T" or "L" shaped liquid ends. The liquid end consists of the stuffing box, pumping chamber, valve assemblies, suction and discharge manifolds. The pumping chamber normally includes intersecting valve passages and plunger bore. The arrangement of intersecting valve passages and plunger bore creates localized areas of high stress, considered limiting factors in the pressure at which the pump could operate. In addition, when valve assemblies are mounted on each side of the plunger bore, the minimum close clearance or residual of the pumping chamber is directly dependent on the physical size of the valve assemblies. The effect of high suction pressures on crosshead pin bushings is a source of lubrication problems in prior art designs. Traditional designs are also limited by the many connections and fasteners which require disassembly during maintenance.